Manufacture of nitric anhydrid



' 1 so two-thirds oi: the oxygen l/f 2; 3% N GUYE, 03E GENEVA, SWITZERLAND, ASSIGNOR T GRGS 6L BQUEI'HARDY; {3F FARIS, FRANCE, A FIEIVZ.

MANUFACTURE OF NITRIC .ANEIYIERID.

@7 concern e ltis linewn that nitric anhyn re by causing ozone to perexicl 8 or with nitric or with nitrogen ti (bl nitric enhyrlrici coni3 are ihier gee ozone being lihereterl.

Ozone cannot be obtained industrially save in e diluted condition in air or oxygen and with the industrial apparatus operaterl by silent electric dischargesthe centration of the ozone is of the order of 10 greros per cubic roster in air or 3 0 grams ber cubic meter '31 pure oxygen. "le s condition appears at first opposed to the inclustriel utilization of the reaction for producing N 0 by causing ozonizecl oxygen to bubble into cooled nitrogen per oxid, because there would be much ol the letter cerriec forward since it has nearly the seine vapor tension as b1 0 st atmcs pheric pressure N59 boils at 21.5%" C. and N 6 sublimes at 31.5 C, whence it follows that it is very difficult to separate elter- Will'd the two borlies N G and N il' currierl' forward by the excess of oxygen wh ch has traversed the liquid nitrogen peroxicl. It is for this reason that llelbig has recommended simply passing a current of ozonizecl oxygen over soli-cl N 6 kept at -20 l and condensing by cold the N 0 1 car lfiil forever-u. By the present invention'there are cause-(l react tit-o currents of gas, one containing least one oxicl nitrogen; of e degree 1 oxidation lower than nitric enhyclrirl, Q and higher than N G, the other con ozone. the two currents being so 7 .w 1 A onggortioneal to each other ines rhere 1s er;-

Specificatios of Letters Patent.

Patented Aeplieation filed Kiley S, 1913, Serial No. 233,543 Q cess neither of ozone nor of oxid of nitro gen; the nitric unhyrlrid I i G which .forms in. the current of gases separated at :1- temperature below -20 C. such as by (h reot cooling to C. or by solution in a solvent cooled to at least 20- (I. and indifferent to nitric anhydrid.

The reactionnioy be carried out with sch vantage in a chamber having an inlet and an outlet for the gases One of the gaseous currents may consist of oxygen or air con taining the oxid of nitrogen, for example nitrogen peroxid, N 0 and the other may consist of ozonized oxygen or air." There may also be directed into the current of ozonized gets (oxygen or air) pure nitrous vapors N 0 in the state of gas, as Well esthe gases NO and N 9 For operating with N U the following is an example of the procedure 2- The speed of the two currents is erij'ustecl in such a. manner that for eucu molecular proportionof N 0 there is one molecular proportion of ozone, the two bodies react immediately the ordinary tempera ture and thereafter the gaseous current contains only nitric anhydrid and the excess of oxygen.

The chief precaution to be observed is the very exact regulation, by means of the usual apparatus for controlling quantities of gas, of the relative volumes of the gases brought together. i v

The nitric enhydricl carried by the gaseous current (oxygen or air) is highly diluted; it is chilled to a temperature sufiiciently low to condense practically the Whole of this anhyclricl.

The investigations preparatory to this invention showed that at -20 (I. the vapor "tension of N 0 is about 7 or nearly one hundredth 01" an atmosphere; out the N 9 produced, being diluted in is large excess of gas (oxygen or air), the whole gaseous mass must be cooled to -80 C. to condense b colrl neerl the Whole (about 99 per cent. of the N 5 produced. The cost of the neoessery refrigeration is diminished. by using after the condensation of N 0 in a suitable condensing apparatus, a heat inter liquid solvents which are indifferent to it; under these conditions the vapor tension of N 0, in solvents less volatile than itself, is lowered and the condensation may be conducted. at temperatures that are not so low as those necessary for recovering pure X 0 Among such solvents pure nitric acid having substantially the composition represented by the formula HNO pure sulfuric ac ll, H SO. and fuming sulfuric acid (mixtures of H 50, and S0 have been found to be particularly interesting from the industrial point of view.

Nitric acid (HXO dissolves up to 30 per cent. of its weight of N 0,; it has then an oily consistence, recalling olive oil, and does not solidify until its temperature is below 80 0.; the solidification curve indicates the presence of a compound having the formula IHKO +N O Sulfuric acid (H dissolves up to 5-2 per cent. of its weight of K 0 and remains liquid above about 50 C; the curve of solidification of mixtures in various proportions discloses the existence of compounds 3X O ,.2HO, and X O LH SO the former, heated in a vacuum at (50 C. is transformed into the latter with disengagement of five-sixths of the dissolved X 0 When using fuming sulfuric acid as solvent for 0 there are obtained, according to the content in $0 various mixtures with X 0 generally solidifying at low temperatures.

All these solutions may be used tor preparing nitrated derivatives and may be sub stituted tor the mixtures of sulfuric and nitric acids hitherto used for nitratious.

hen the object is the obtaining ot pure N 0, there may be used advantageously as solvent a substance which does not form complexes with this anh vdrid. To this category belongs. among others. carbon tetrachlorid (boiling )oint 76.5 from which the anhydrid may be recovered by fractional distillation.

. Whatever solvent is used the temperature for nearly complete condensation of the Having now fully described the nature of my said invention and the best means I know ot carrying the same into practical effect, I claim l. A. process for making continuously nitric anhydrid N 0 by the reaction of ozone on an oxid of nitrogen of a degree ot oxidation lower than K 0 and higher than N t), wherein two gaseous currents, one containing at least one of the said oxide of nitrogen, the other containing ozone, are caused to react in such proportion to each other that there is present an excess neither of ozone nor of oxid ot nitrogen, the nitric-anhydrid which is formed being recovered from the gaseous current at a temperature below 20 C.

2. A process according to claim 1, w the nitric anhydrid is separated from ierein the gaseous current by solution in a solvent which is cooled to at least 20 C. and is without substantial efi'ect, on the chemical properties of the anhydrid.

A process according to claim 1, wherein the nitric anhydrid is separated from the gaseous current by solution in concentrated nitric acid, HXO which is cooled to at least QO C.

l. A process according to claim 1, wherein the chilled gases issuing from the recovery apparatus pass through a heat interchanger where they cool, gases charged with N 0 entering the recovery apparatus.

In testimony whereof I have signed my name to this specification'in the presence of two subscribing witnesses.

PHILIPPE AUGUSTE GUY.

Witnesses LOL'lS H. Memoir, J. Divonxn. 

